JP6047342B2 - Negative electrode for power storage device - Google Patents

Description

The present invention relates to a negative electrode for a power storage device and a power storage device having the negative electrode.

Amid growing interest in environmental issues, the development of power storage devices such as secondary batteries and electric double layer capacitors that can be used for power sources for hybrid vehicles and the like has been actively developed. As such candidates, power storage devices such as lithium (Li) ion secondary batteries and Li ion capacitors with high energy performance are attracting attention. Li-ion secondary batteries can store large amounts of electricity even when they are small, so they are already installed in portable information terminals such as mobile phones and notebook personal computers, and play a role in miniaturization of products.

The basic configuration of the power storage device is a configuration in which an electrolyte is interposed between the positive electrode and the negative electrode. As the positive electrode and the negative electrode, a configuration having a current collector and an active material provided on the current collector is known. For example, a Li ion secondary battery uses a material that can occlude and release Li ions as an active material.

In order to improve the characteristics of the power storage device, various approaches have been taken. For example, a study of a negative electrode active material for a power storage device is one of them. The mainstream graphite-based carbon material as the negative electrode active material has a theoretical capacity of 372 mAh / g, and has already been put to practical use at a value close to the theoretical capacity. Therefore, an active material having a larger capacity (charging capacity) is required.

As a material having a larger capacity than a graphite-based carbon material when used as a negative electrode active material of a power storage device, there is a material containing a metalloid, a metalloid compound, a metal, or a metal compound. For example, silicon (Si) is known to have a higher capacity than graphite-based carbon materials, and Patent Document 1 discloses Li ions using fibrous carbon materials, silicon and silicon compounds in addition to graphite-based carbon materials. A negative electrode for a secondary battery is disclosed. Patent Document 2 discloses a Li ion secondary battery using a graphite-based carbon material and a metal-carbon composite material.

However, with a demand for further downsizing of the power storage device, a negative electrode active material having a larger capacity is demanded.

JP 2004-182512 A JP 2009-105046 A

In view of the above, an object of one embodiment of the present invention is to provide a negative electrode active material with larger capacity.

In order to achieve the above object, according to one embodiment of the present invention, as a negative electrode active material, amorphous PAHs (polycyclic aromatic hydrocarbons), a carrier ion storage metal, a carrier ion storage alloy, a metal compound, Si, , Sb, or SiO ₂ and a mixture thereof was used. Note that in this specification and the like, a carrier ion storage metal refers to a metal that can store and release carrier ions in a power storage device. Similarly, a carrier ion storage alloy refers to an alloy that can store and release carrier ions in a power storage device.

The theoretical capacity of amorphous PAHs is 1116 mAh / g, and the experimental capacity is 680 mAh / g, which greatly exceeds the theoretical capacity of 372 mAh / g of the graphite-based carbon material. Therefore, by using amorphous PAHs, it is possible to increase the capacity of the negative electrode active material as compared with the case of using a graphite-based carbon material.

Furthermore, in the case of amorphous PAHs only by mixing amorphous PAHs that are large-capacity materials and one or more of carrier ion storage metal, carrier ion storage alloy, metal compound, Si, Sb, or SiO ₂ The negative electrode active material can increase the capacity.

One embodiment of the present invention includes amorphous PAHs, a carrier ion storage metal, a carrier ion storage alloy, a metal compound, a negative electrode active material containing any one or more of Si, Sb, and SiO ₂ , and a current collector. This is a negative electrode for a power storage device.

Further, the carrier ion storage metal may be any one of Sn, Al, Zn, or Bi. The carrier ion storage alloy may be any one of alloys represented by Sn-M alloys (M is Fe, Co, Mn, V, or Ti). As the metal compound, an Sn compound or a metal compound used as a positive electrode material in a state where carrier ions are reduced (decarrier ion state) can be used. As the Sn compound, any one of SnO ₂ , Sn ₂ P ₂ O ₇ , and SnPBO ₆ may be used. Further, the metal compound used as the positive electrode material in a state where carrier ions are reduced (decarrier ion state) may be any one of SnPO ₄ ClCoO, NiO, MnO ₂ , and FePO ₄ .

In the above, the carrier ions may be any one of Li ions or Na ions.

The amorphous PAHs may be spherical.

Moreover, any one or more of a metal, a metal compound, Si, Sb, or SiO ₂ may adhere to the surface of the amorphous PAHs.

In addition, any one or more of a metal, a metal compound, Si, Sb, or SiO ₂ may be contained in the range of 1 wt% to 50 wt% with respect to the amorphous PAHs.

Another embodiment of the present invention is a power storage device including the above negative electrode, a positive electrode, and an electrolytic solution containing an electrolyte.

According to one embodiment of the present invention, a negative electrode active material with larger capacity can be provided.

The schematic diagram of an example of a negative electrode active material and a negative electrode. 4A and 4B are a plan view and a cross-sectional view illustrating one embodiment of a power storage device. 4A and 4B illustrate an application mode of a power storage device. The scanning electron micrograph of an example of a negative electrode active material. The scanning electron micrograph of an example of a negative electrode active material. The figure which shows the evaluation result of an example of a negative electrode. The figure which shows the evaluation result of an example of a negative electrode. The figure which shows the evaluation result of an example of a negative electrode.

Hereinafter, embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the description of the embodiments described below, and it is obvious to those skilled in the art that modes and details can be variously changed without departing from the spirit of the invention disclosed in this specification and the like. . In addition, structures according to different embodiments can be implemented in appropriate combination. Note that in the structures of the invention described below, the same portions or portions having similar functions are denoted by the same reference numerals, and repetitive description thereof is omitted.

Note that the position, size, range, and the like of each component illustrated in the drawings and the like may not represent the actual position, size, range, or the like for easy understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, range, or the like disclosed in the drawings and the like.

(Embodiment 1)
In this embodiment, a negative electrode active material for a power storage device which is one embodiment of the present invention and a manufacturing method thereof will be described with reference to FIGS.

<Negative electrode active material>
Hereinafter, an example of the negative electrode active material 100 will be described with reference to FIG. The negative electrode active material 100 includes amorphous PAHs 101 and fine particles 102 made of any one of a metal, a metal compound, Si, Sb, or SiO ₂ . Furthermore, you may have the secondary particle 103 which the some fine particle 102 aggregated.

As the amorphous PAHs 101, PAHs having an H / C ratio (ratio of carbon and hydrogen atoms) of 0.05 or more and 0.5 or less are used. Hereinafter, the atomic ratio of carbon and hydrogen is referred to as the H / C ratio. As the amorphous PAHs having an H / C ratio of 0.05 or more and 0.5 or less, for example, polyacene materials, hard carbon materials, and the like can be used.

The polyacene-based material has a large capacity (about 850 mAh / g) compared to the graphite-based carbon material. The hard carbon material also has a large capacity (about 400 to 700 mAh / g) compared to the graphite carbon material, and has a discharge characteristic that the voltage drops uniformly to the discharge end voltage. Therefore, it is preferable to use these for the negative electrode active material because a power storage device with high energy density can be obtained.

Further, when the amorphous PAHs 101 is spherical, variation in contact area with other negative electrode components is reduced. Therefore, it is preferable that the unevenness of resistance in the negative electrode active material layer is reduced. Spherical materials are preferred because they have less wear during transportation, can be easily filled with high density, and can improve fluidity when mixed with other negative electrode components. Specifically, amorphous PAHs 101 having a particle diameter of 100 μm or less is preferable.

In the present specification and the like, the spherical shape does not need to be a strict spherical shape. For example, a substantially spherical shape (for example, the shortest diameter is 70% or more and less than 100% of the longest diameter), a distorted sphere, a sphere having a protrusion on the surface, an elliptic sphere, and the like are included.

In this embodiment, a spherical polyacene material is used as the amorphous PAHs 101.

A metal, a metal compound, Si, Sb, or SiO ₂ is mixed with the amorphous PAHs 101.

As the metal to be mixed, a carrier ion storage metal is used. As the metal compound to be mixed, a carrier ion storage alloy or a metal compound is used.

As the carrier ions, Li ions, alkali metal ions such as sodium (Na) ions, alkaline earth metal ions, beryllium (Be) ions, magnesium (Mg) ions, or the like can be used. By using Li ions as carrier ions, a power storage device having characteristics such as a small memory effect, a high energy density, a large charge / discharge capacity, and a high output voltage is preferable. Further, since Na ions are abundant in resource, they are preferably used as carrier ions because the manufacturing cost of the power storage device can be reduced. In this embodiment, Li ions are used as carrier ions.

As the carrier ion storage metal to be mixed, a metal having a property of storing carrier ions, for example, Sn, Al, Zn, or Bi can be used.

As the carrier ion storage alloy to be mixed, an alloy having a property of storing carrier ions, for example, an alloy represented by Sn-M (M is Fe, Co, Mn, V, or Ti) can be used.

As the metal compound to be mixed, a Sn compound or a metal compound used as a positive electrode material in a state where carrier ions are reduced (decarrier ion state) can be used. As the Sn compound, for example, SnO ₂ , Sn ₂ P ₂ O ₇ , SnPBO ₆ , or SnPO ₄ Cl can be used. In addition, as a metal compound used as a positive electrode material in a state where carrier ions are reduced (de-carrier ion state), among materials that can be used as a positive electrode active material of a power storage device, a material that is stable even when no carrier ions are present For example, CoO, NiO, MnO ₂ , NiMnO ₄ or FePO ₄ can be used.

The fine particles 102 are particles made of a metal, a metal compound, Si, Sb, or SiO ₂ . In order to increase the efficiency of the reaction with the carrier ions, for example, the particle size is preferably set to 1 μm or less, for example.

The metal, metal compound, Si, Sb, or SiO ₂ fine particles 102 may or may not adhere to the outer surface of the amorphous PAHs 101. The fine particles 102 of metal, metal compound, Si, Sb, or SiO ₂ may form secondary particles 103. The secondary particles 103 may or may not adhere to the outer surface of the amorphous PAHs 101. However, the fine particles 102 of metal, metal compound, Si, Sb, or SiO ₂ are more preferably adhered to the amorphous PAHs 101 without being aggregated. This is because the fine particles 102 have a larger specific surface area than the aggregated secondary particles 103 and are likely to react with carrier ions. When the fine particles 102 are attached to the amorphous PAHs 101, it is difficult to form the secondary particles 103.

Further, the metal, metal compound, Si, Sb, or SiO _{2 to} be mixed is preferably contained in the range of 1% by weight to 50% by weight with respect to the amorphous PAHs 101, and in the range of 1% by weight to 30% by weight. More preferably, it is contained. If the amount of the metal, metal compound, Si, Sb, or SiO _{2 to} be mixed is too small, the effect of increasing the capacity of the power storage device is reduced. However, if the amount is too large, the electrical conductivity of the negative electrode active material becomes too low, which is preferable. Absent. In the present embodiment, 1 wt% or more and 30 wt% or less of SiO ₂ is mixed with the amorphous PAHs 101.

<Negative electrode>
An example of the negative electrode 200 for a power storage device according to one embodiment of the present invention will be described below with reference to FIGS.

A negative electrode 200 in FIG. 1B includes a negative electrode active material 100, a conductive auxiliary agent 120, and a binder (not shown in FIG. 1B) on a negative electrode current collector 130.

As the negative electrode current collector 130, a conductive material such as copper (Cu), titanium (Ti), aluminum (Al), or stainless steel that has a foil shape, a plate shape, a net shape, or the like can be used.

As the conductive auxiliary agent 120, an electron conductive material that does not cause a chemical change in the power storage device is used. For example, graphite, carbon particles, carbon fibers, or the like, metal materials such as Cu, nickel (Ni), Al, or silver (Ag), or powders or fibers of a mixture thereof can be used. In the negative electrode 200 in FIG. 1B, acetylene black which is one of carbon particles is used.

The binder exists between the negative electrode active material 100, the conductive auxiliary agent 120, and the negative electrode current collector 130, and bonds them together. Binders include polysaccharides such as starch, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyethylene, polypropylene, polyvinyl alcohol, polyvinyl pyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride, EPDM. (Ethylene Propylene Diene Monomer) Rubber, vinyl polymer such as sulfonated EPDM rubber, styrene butadiene rubber, butadiene rubber, fluoro rubber, and polyether such as polyethylene oxide. In this embodiment, PVdF is used.

The negative electrode active material layer may be predoped with carrier ions. When Li ions are used as carrier ions, as a pre-doping method, a Li layer may be formed on the surface of the negative electrode active material layer by a sputtering method. Alternatively, Li can be pre-doped into the negative electrode active material layer by providing a Li foil on the surface of the negative electrode active material layer.

Further, as shown in FIG. 1C, graphene or multilayer graphene 121 may be used instead of the conductive additive 120 and the binder. By using the graphene or the multilayer graphene 121, the influence (expansion and pulverization of the negative electrode active material 100 and separation of the negative electrode active material layer) exerted by the expansion and contraction of the negative electrode active material 100 that accompanies the insertion and extraction of carrier ions is suppressed. be able to. In addition, since graphene or multilayer graphene 121 occludes carrier ions and functions as a negative electrode active material, the negative electrode can have a larger capacity.

<Method for producing negative electrode active material>
An example of a method for producing a negative electrode active material is described below.

First, a material for amorphous PAHs is prepared. When a polyacene material is used as the amorphous PAHs 101, for example, a phenol resin can be used as a raw material for the polyacene material. When a polyacene-based material is used, productivity can be improved because the firing temperature can be lowered in firing described later.

When a hard carbon material is used as the amorphous PAHs 101, a sugar such as a furfuryl alcohol resin, sucrose, or cellulose can be used as a raw material for the hard carbon material.

Note that cleaning is preferably performed to remove organic impurities attached to the amorphous PAHs 101. For example, ultrasonic cleaning may be performed in an organic solvent.

Next, a metal, a metal compound, Si, Sb, or SiO ₂ is mixed with the material of the amorphous PAHs 101. For the metal, metal compound, Si, Sb, or SiO _{2, the} description of FIG. 1A can be referred to.

In this embodiment, a polyacene material is used as the amorphous PAHs 101, and a spherical phenol resin is used as a raw material for the polyacene material. This is mixed with SiO ₂ fine particles.

The mixing method is not particularly limited, but for example, dry mixing can be performed. In addition, when using spherical phenol resin, it is preferable to carry out by the method which can maintain the shape, for example, it is preferable to perform mixing by a rotating roller.

Next, a mixture of the amorphous PAHs 101 material and a metal, a metal compound, Si, Sb, or SiO ₂ is fired. Firing is preferably performed in an inert atmosphere, for example, in a nitrogen atmosphere. The firing temperature and time may be set under conditions sufficient for carbonization of the amorphous PAHs 101 material. For example, when a phenol resin is used, the firing temperature can be 600 ° C. or higher and 800 ° C. or lower. Although the method is not particularly limited, it can be performed using a muffle furnace or the like.

By the above method, the negative electrode active material 100 which is one embodiment of the present invention can be manufactured.

<Method for producing negative electrode>
Hereinafter, an example of a method for manufacturing the negative electrode 200 using the negative electrode active material 100 will be described.

First, the negative electrode active material 100, the conductive additive 120, and a binder are mixed using a solvent to prepare a slurry. Although the solvent is not particularly limited, for example, an organic solvent such as N-methyl-2-pyrrolidone (NMP) can be used.

Instead of the conductive assistant 120 and the binder, graphene or multilayer graphene 121 may be used. Note that in this specification, graphene refers to a sheet of carbon molecules having a single atomic layer having sp ² bonds. Multilayer graphene is a stack of 2 to 100 graphene, and the multilayer graphene may contain elements other than carbon such as oxygen and hydrogen at 30 atomic% or less. Moreover, 15 atomic% or less of elements other than carbon and hydrogen may be contained. Note that graphene and multilayer graphene may be ones to which an alkali metal such as Li, Na, or potassium (K) is added.

Next, the slurry is applied to the negative electrode current collector 130. In order to improve the adhesion between the negative electrode current collector 130 and the negative electrode active material 100, an anchor coating agent may be applied before applying the slurry. The slurry containing the negative electrode active material 100 may be applied to one surface of the negative electrode current collector 130 as shown in FIGS. 1B and 1C, or may be applied to both surfaces.

Next, the negative electrode current collector 130 and the slurry are dried to form the negative electrode 200 in a desired shape, and then further dried.

By the above method, the negative electrode 200 which is one embodiment of the present invention can be manufactured.

(Embodiment 2)
In this embodiment, an example of a power storage device according to one embodiment of the present invention will be described with reference to FIGS.

The power storage device according to one embodiment of the present invention includes at least a positive electrode, a negative electrode, a separator, and an electrolytic solution. The negative electrode is the negative electrode described in Embodiment 1.

The electrolytic solution is a non-aqueous solution containing an electrolyte salt or an aqueous solution containing an electrolyte salt. The electrolyte salt may be an electrolyte salt containing alkali metal ions, alkaline earth metal ions, Be ions, or Mg ions that are carrier ions. Examples of the alkali metal ion include Li ion, Na ion, and K ion. Examples of alkaline earth metal ions include calcium (Ca) ions, strontium (Sr) ions, and barium (Ba) ions. In the present embodiment, the electrolyte salt is an electrolyte salt containing Li ions (hereinafter referred to as Li-containing electrolyte salt).

By setting it as the said structure, it can be set as a secondary battery or a capacitor. Moreover, it can be set as an electric double layer capacitor by using only a solvent as electrolyte solution, without using electrolyte salt.

Here, the power storage device will be described with reference to the drawings.

FIG. 2A illustrates an example of the structure of the power storage device 351. FIG. 2B is a cross-sectional view taken along one-dot chain line X-Y in FIG.

A power storage device 351 illustrated in FIG. 2A includes a power storage cell 355 inside an exterior member 353. In addition, terminal portions 357 and 359 connected to the storage cell 355 are provided. As the exterior member 353, a laminate film, a polymer film, a metal film, a metal case, a plastic case, or the like can be used.

As shown in FIG. 2B, the power storage cell 355 includes a negative electrode 363, a positive electrode 365, a separator 367 provided between the negative electrode 363 and the positive electrode 365, and an electrolytic solution 369 filled in the exterior member 353. Is done.

The negative electrode 363 is the negative electrode described in Embodiment 1. The negative electrode current collector 371 is connected to the terminal portion 359. The positive electrode current collector 375 is connected to the terminal portion 357.

Further, a part of each of the terminal portion 357 and the terminal portion 359 is led out to the outside of the exterior member 353.

The positive electrode 365 includes a positive electrode current collector 375 and a positive electrode active material layer 377. The positive electrode active material layer 377 is formed on one or both surfaces of the positive electrode current collector 375. In addition to the positive electrode current collector 375 and the positive electrode active material layer 377, the positive electrode 365 may include a binder, a conductive additive, and the like.

Note that although a sealed thin power storage device is shown as an external form of the power storage device 351 in this embodiment, the present invention is not limited to this. As the external form of the power storage device 351, various shapes such as a button-type power storage device, a cylindrical power storage device, and a rectangular power storage device can be used. In this embodiment mode, a structure in which the positive electrode, the negative electrode, and the separator are stacked is shown; however, a structure in which the positive electrode, the negative electrode, and the separator are wound may be used.

As the positive electrode current collector 375, a conductive material such as Al or stainless steel having a foil shape, a plate shape, a net shape, or the like is used. Alternatively, the conductive layer provided by being separately formed over the substrate can be peeled to be used as the positive electrode current collector 375.

The positive electrode active material layer 377 is made of LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiMnO ₄ , LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , LiMn ₂ PO ₄ , V ₂ O ₅ , MnO ₂ , and other Li compounds. Can do. When the carrier ions are alkali metal ions other than Li ions, alkaline earth metal ions, Be ions, or Mg ions, an alkali metal (for example, instead of Li in the Li compound) is used as the positive electrode active material layer 377. , Na or K), alkaline earth metals (for example, Ca, Sr or Ba), Be or Mg may be used. For example, when the carrier ion is Na ion, NaNi _0.5 Mn _0.5 O ₂ can be used.

The positive electrode 365 can be manufactured by forming the positive electrode active material layer 377 over the positive electrode current collector 375 by a coating method or a physical vapor deposition method (for example, a sputtering method). In the case of using the coating method, a conductive auxiliary agent (for example, acetylene black) or a binder (for example, PVDF) is mixed with the material of the above-described positive electrode active material layer 377 to form a paste, which is coated on the positive electrode current collector 375. The positive electrode 365 is formed by drying. At this time, the positive electrode 365 may be pressure-molded as necessary.

In the positive electrode active material layer 377, graphene or multilayer graphene may be mixed with the positive electrode active material instead of the conductive additive and the binder.

By using graphene or multilayer graphene instead of the conductive assistant and the binder, the contents of the conductive assistant and the binder in the positive electrode 365 can be reduced. That is, the weight of the positive electrode 365 can be reduced, and as a result, the charge / discharge capacity of the power storage device per weight of the negative electrode can be increased.

Strictly speaking, the “active material” of the positive electrode or the negative electrode refers only to a material related to insertion and extraction of ions as carriers. However, in this specification, when an active material layer is formed using a coating method, for the sake of convenience, the material of the active material layer, that is, the material that is originally an “active material”, including a conductive auxiliary agent, a binder, etc. I will call it.

As described above, the electrolytic solution 369 is a non-aqueous solution containing an electrolyte salt or an aqueous solution containing an electrolyte salt. In particular, Li ion secondary batteries use Li-containing electrolyte salts that can transport Li ions that are carrier ions and that Li ions can exist stably. Examples of the Li-containing electrolyte salt include LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiPF ₆ , and Li (C ₂ F ₅ SO ₂ ) ₂ N. Note that when the carrier ion is an alkali metal ion or alkaline earth metal ion other than Li, as the solute of the electrolytic solution 369, an alkali metal salt (for example, Na salt or K salt), an alkaline earth metal salt ( For example, Ca salt, Sr salt or Ba salt), Be salt or Mg salt can be used. For example, when Na ions are used as carrier ions, NaPF ₆ , NaClO ₄ or the like can be used as a solute (electrolyte salt).

The electrolyte solution 369 is preferably a non-aqueous solution containing an electrolyte salt. That is, the solvent of the electrolytic solution 369 is preferably an aprotic organic solvent. Examples of the aprotic organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, acetonitrile, dimethoxyethane, and tetrahydrofuran, and one or more of these can be used. Furthermore, one ionic liquid or a plurality of ionic liquids may be used as the aprotic organic solvent. Since the ionic liquid is flame retardant and volatile, when the internal temperature of the power storage device 351 rises, the rupture or ignition of the power storage device 351 can be suppressed, and safety can be improved.

In addition, by using a gelled polymer material that includes an electrolyte salt as the electrolytic solution 369, safety including liquid leakage is increased, and the power storage device 351 can be thinned and lightened. Typical examples of the polymer material to be gelated include silicon gel, acrylic gel, acrylonitrile gel, polyethylene oxide, polypropylene oxide, and fluorine-based polymer.

Further, as the electrolytic solution 369, a solid electrolyte such as Li ₃ PO ₄ can be used.

As the separator 367, an insulating porous body is used. For example, paper, non-woven fabric, glass fiber, nylon (polyamide), vinylon (polyvinyl alcohol fiber), polyester, acrylic, polyolefin, polyurethane, synthetic fiber such as polyurethane, ceramics, or the like may be used. However, it is necessary to select a material that does not dissolve in the electrolyte solution 369.

In the case where the power storage device according to one embodiment of the present invention is a Li ion capacitor, a material that can reversibly store and release one or both of Li ions and anions may be used instead of the positive electrode active material layer 377. Examples of the material include activated carbon, graphite, a conductive polymer, and a polyacene material.

With the use of the negative electrode active material according to one embodiment of the present invention, a large-capacity power storage device can be obtained.

Note that this embodiment can be implemented in appropriate combination with the structures described in the other embodiments or examples.

(Embodiment 3)
The power storage device according to one embodiment of the present invention can be used as a power source for various electric devices and electronic devices that are driven by electric power.

Specific examples of electrical and electronic devices using the power storage device according to one embodiment of the present invention are stored in a recording medium such as a display device, a lighting device, a desktop or laptop personal computer, or a DVD (Digital Versatile Disc). Image reproduction device for reproducing still images or moving images, mobile phones, portable game machines, portable information terminals, tablet terminals, electronic books, video cameras, digital still cameras, microwave ovens and other high-frequency heating devices, electric rice cookers, Examples include air-conditioning equipment such as an electric washing machine and an air conditioner, electric refrigerators, electric freezers, electric refrigerator-freezers, DNA storage freezers, medical electric devices such as dialysis machines, and electronic devices. In addition, moving objects driven by an electric motor using electric power from a power storage device are also included in the category of electric devices and electronic devices. Examples of the moving body include an electric vehicle, a hybrid vehicle having both an internal combustion engine and an electric motor, and a motor-equipped bicycle including an electric assist bicycle.

Note that the electrical device and the electronic device can use the power storage device according to one embodiment of the present invention as a power storage device (referred to as a main power supply) for supplying almost all of the power consumption. Alternatively, the electric device and the electronic device can be a power storage device (referred to as an uninterruptible power supply) that can supply power to the electric device and the electronic device when the supply of power from the main power supply or the commercial power supply is stopped. ), The power storage device according to one embodiment of the present invention can be used. Alternatively, the electric device and the electronic device may include a power storage device for supplying electric power to the electric device and the electronic device in parallel with the supply of electric power to the electric device and the electronic device from the main power source or the commercial power source ( The power storage device according to one embodiment of the present invention can be used as an auxiliary power source.

FIG. 3 shows specific structures of the electric device and the electronic device. In FIG. 3, a display device 1000 is an example of an electronic device including the power storage device 1004 according to one embodiment of the present invention. Specifically, the display device 1000 corresponds to a display device for TV broadcast reception, and includes a housing 1001, a display portion 1002, a speaker portion 1003, a power storage device 1004, and the like. A power storage device 1004 according to one embodiment of the present invention is provided in the housing 1001. The display device 1000 can receive power from a commercial power supply. Alternatively, the display device 1000 can use power stored in the power storage device 1004. Thus, the display device 1000 can be used by using the power storage device 1004 according to one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power supply due to a power failure or the like.

The display portion 1002 includes a liquid crystal display device, a light emitting device including a light emitting element such as an organic EL element in each pixel, an electrophoretic display device, a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), and an FED (Field Emission Display). For example, a semiconductor display device can be used.

The display device includes all information display devices such as a personal computer and an advertisement display in addition to a TV broadcast reception.

In FIG. 3, a stationary lighting device 1100 is an example of an electrical device using the power storage device 1103 according to one embodiment of the present invention. Specifically, the lighting device 1100 includes a housing 1101, a light source 1102, a power storage device 1103, and the like. FIG. 3 illustrates the case where the power storage device 1103 is provided inside the ceiling 1104 where the housing 1101 and the light source 1102 are installed, but the power storage device 1103 is provided inside the housing 1101. May be. The lighting device 1100 can receive power from a commercial power supply. Alternatively, the lighting device 1100 can use power stored in the power storage device 1103. Thus, the lighting device 1100 can be used by using the power storage device 1103 according to one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power supply due to a power failure or the like.

Note that FIG. 3 illustrates a stationary lighting device 1100 provided on the ceiling 1104; however, a power storage device according to one embodiment of the present invention can be provided on a side wall 1105, a floor 1106, a window 1107, or the like other than the ceiling 1104. It can be used for a stationary lighting device provided, or can be used for a desktop lighting device or the like.

As the light source 1102, an artificial light source that artificially obtains light using electric power can be used. Specifically, discharge lamps such as incandescent bulbs and fluorescent lamps, and light emitting elements such as LEDs and organic EL elements are examples of the artificial light source.

In FIG. 3, an air conditioner including an indoor unit 1200 and an outdoor unit 1204 is an example of an electrical device using the power storage device 1203 according to one embodiment of the present invention. Specifically, the indoor unit 1200 includes a housing 1201, a blower opening 1202, a power storage device 1203, and the like. 3 illustrates the case where the power storage device 1203 is provided in the indoor unit 1200, the power storage device 1203 may be provided in the outdoor unit 1204. Alternatively, the power storage device 1203 may be provided in both the indoor unit 1200 and the outdoor unit 1204. The air conditioner can receive power from a commercial power supply. Alternatively, the air conditioner can use power stored in the power storage device 1203. In particular, in the case where the power storage device 1203 is provided in both the indoor unit 1200 and the outdoor unit 1204, the power storage device 1203 according to one embodiment of the present invention is not used even when power supply from a commercial power source cannot be received due to a power failure or the like. By using it as a power failure power supply, an air conditioner can be used.

In FIG. 3, a separate type air conditioner composed of an indoor unit and an outdoor unit is illustrated. However, an integrated air conditioner having the functions of the indoor unit and the outdoor unit in one housing is shown. The power storage device according to one embodiment of the present invention can also be used.

In FIG. 3, an electric refrigerator-freezer 1300 is an example of an electrical device using the power storage device 1304 according to one embodiment of the present invention. Specifically, the electric refrigerator-freezer 1300 includes a housing 1301, a refrigerator door 1302, a freezer door 1303, a power storage device 1304, and the like. In FIG. 3, the power storage device 1304 is provided inside the housing 1301. The electric refrigerator-freezer 1300 can receive power from a commercial power supply. Alternatively, the electric refrigerator-freezer 1300 can use power stored in the power storage device 1304. Therefore, the electric refrigerator-freezer 1300 can be used by using the power storage device 1304 according to one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power supply due to a power failure or the like.

Note that among the electric devices described above, a high-frequency heating device such as a microwave oven and an electric device such as an electric rice cooker require high power in a short time. Therefore, by using the power storage device according to one embodiment of the present invention as an auxiliary power source for assisting electric power that cannot be covered by a commercial power source, a breaker of the commercial power source can be prevented from falling when an electric device is used.

In addition, the time period when the electrical equipment and electronic equipment are not used, particularly the time period when the ratio of the actually used power amount (referred to as the power usage rate) is low in the total power amount that can be supplied by the commercial power source. Therefore, by storing the power in the power storage device, it is possible to suppress an increase in the power usage rate outside the time period. For example, in the case of the electric refrigerator-freezer 1300, electric power is stored in the power storage device 1304 at night when the temperature is low and the refrigerator door 1302 and the refrigerator door 1303 are not opened and closed. In the daytime when the temperature rises and the refrigerator door 1302 and the freezer door 1303 are opened and closed, the power storage device 1304 is used as an auxiliary power source, so that the daytime power usage rate can be kept low.

In FIG. 3, a tablet terminal 1400 is an example of an electronic device using the power storage device 1403 according to one embodiment of the present invention. Specifically, the tablet terminal 1400 includes a housing 1401, a housing 1402, a power storage device 1403, and the like. Each of the housing 1401 and the housing 1402 includes a display portion having a touch panel function, and the display contents of the display portion can be operated by touching a finger or the like. In addition, the tablet terminal 1400 can be folded with the display portions of the housing 1401 and the housing 1402 inside, and thus the size of the tablet terminal 1400 can be reduced and the display portion can be protected. By using the power storage device 1403 according to one embodiment of the present invention, the tablet terminal 1400 can be downsized and used for a long time.

Note that this embodiment can be implemented in appropriate combination with the structures described in the other embodiments or examples.

In this example, the result of actually producing a negative electrode active material for a power storage device which is one embodiment of the present invention and evaluating the characteristics thereof will be described with reference to FIGS.

<Preparation of negative electrode active material>
In this example, spherical phenol resin (Marilyn HF-008, manufactured by Gunei Chemical Industry Co., Ltd.) was used as a raw material for amorphous PAHs. It was 9.6 micrometers when the average particle diameter was measured with the particle size distribution analyzer.

SiO ₂ was mixed with the raw material of the amorphous PAHs. As SiO ₂ , SiO ₂ nano powder (manufactured by Aldrich) having a particle diameter of 10 to ₂₀ nm was used.

First, ultrasonic cleaning was performed in acetone to remove organic impurities attached to the spherical phenol resin.

Next, SiO ₂ nanopowder was added to the washed spherical phenol resin, and dry-mixed with a rotating roller. As shown in Table 1 below, the addition amount is 0 wt% of SiO ₂ nanopowder (0 g [reference example]), 1 wt% addition (0.05 g), and 10 wt% addition (0.50 g) to 5 g of spherical phenol resin. ), 20 wt% added (1.00 g) and 30 wt% added (1.50 g).

Next, the mixture of spherical phenol resin and SiO ₂ nano powder was fired to obtain a negative electrode active material. Firing was performed using a muffle furnace in a nitrogen atmosphere (N ₂ 5 L / min) at 700 ° C. for 10 hours. Table 1 shows the weight yield after firing.

Scanning electron micrographs of the negative electrode active material produced as described above are shown in FIGS. 4A is a negative electrode active material in which SiO ₂ nanopowder is added at 0 wt% [reference example], FIG. 4B is a negative electrode active material in which 1 wt% of SiO ₂ nanopowder is added to a spherical phenol resin, and FIG. negative electrode active material and the SiO ₂ nanopowder was added 20 wt% spherical phenol resin, FIG. 5 (B) is a negative electrode active material and the SiO ₂ nanopowder was added 30 wt% spherical phenolic resin. In FIG. 4 (B), FIG. 5 (A) and FIG. 5 (B), a state where SiO ₂ nanopowder was adhered to the outer surface of the spherical phenol resin was observed.

<Production of negative electrode>
A negative electrode was produced using the above negative electrode active material. In addition to the negative electrode active material as a negative electrode material, acetylene black was used as a conductive additive, PVdF was used as a binder, and Cu foil was used as a current collector. The compounding ratio of the negative electrode active material, acetylene black, and PVdF was 82 wt% for the negative electrode active material, 8 wt% for acetylene black, and 10 wt% for PVdF.

First, the negative electrode active material and PVdF were mixed with a homogenizer using NMP as a solvent. Acetylene black was added to this and further mixed. Further, the viscosity was adjusted with NMP to obtain a slurry. After applying an anchor coating agent to the Cu foil current collector to about 1 to 2 μm, a slurry was applied.

Next, the Cu foil current collector and the slurry were dried at 70 ° C. for 15 minutes using a ventilation dryer. This was punched out into a circle having a diameter of 16.15 mm and dried at 170 ° C. for 10 hours using a vacuum furnace to obtain a negative electrode.

Table 2 shows the thickness and density of the negative electrode produced as described above. As shown in Table 2, a negative electrode having the same electrode thickness and density under each condition could be produced.

<Evaluation of negative electrode>
About the negative electrode produced as mentioned above, charging / discharging capacity | capacitance and efficiency were measured and the charging / discharging characteristic was evaluated.

In order to evaluate the charge / discharge characteristics, a cell was produced using the negative electrode produced as described above as the working electrode and Li metal having a diameter of 15 mm as the counter electrode. Glass fiber filter paper is used for the separator, and 1 mol / L lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a mixed solution of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (volume ratio 3: 7) for the electrolyte. Used.

Charging was performed with a drive system CCCV (constant current-constant voltage), a current value of 0.2 C (1.3 mA), a lower limit voltage of 1 mV, and an end current of 10 μA. Discharging was performed with a drive system CC (constant current), a current value of 0.2 C (1.3 mA), and an upper limit voltage of 2V.

The results of evaluation of charge / discharge characteristics are shown in FIGS. FIG. 6 shows only the spherical phenol resin (0 wt% added [reference example]), FIG. 7 shows the addition of 1 wt% of SiO ₂ nanopowder to the spherical phenol resin, and FIG. 8 shows the negative electrode active with 30 wt% of SiO ₂ nano powder added to the spherical phenol resin. It is the charging / discharging characteristic of the negative electrode using a substance. All measurements were performed with 2 samples. The vertical axis represents voltage, and the horizontal axis represents capacity.

In the case of only the spherical phenol resin of FIG. 6 (addition of 0 wt% [reference example]), the maximum charge capacity was 1076.7 mAh / g, the discharge capacity was 433.2 mAh / g, and the efficiency was 40.8%.

In contrast, when 1 wt% of SiO ₂ nanopowder was added to the spherical phenol resin of FIG. 7, the maximum charge capacity was 1116.6 mAh / g, the discharge capacity was 467.6 mAh / g, and the efficiency was 42.3%. .

Further, when 30 wt% of SiO ₂ nanopowder was added to the spherical phenol resin of FIG. 8, the maximum charge capacity was 1730.0 mAh / g, the discharge capacity was 633.2 mAh / g, and the efficiency was 39.4%.

From the above results, it has been clarified that the charge capacity and the discharge capacity are improved by adding SiO ₂ nanopowder to the spherical phenol resin. Further, it has been clarified that the charge capacity and the discharge capacity are further improved when 30 wt% of SiO ₂ nanopowder is added than when 1 wt% is added.

100 Negative electrode active material 101 Amorphous PAHs
102 Fine particles 103 Secondary particles 120 Conductive aid 121 Multilayer graphene 130 Negative electrode current collector 200 Negative electrode 351 Power storage device 353 Exterior member 355 Power storage cell 357 Terminal portion 359 Terminal portion 363 Negative electrode 365 Positive electrode 367 Separator 369 Electrolyte 371 Negative electrode current collector 375 Positive electrode current collector 377 Positive electrode active material layer 1000 Display device 1001 Case 1002 Display portion 1003 Speaker portion 1004 Power storage device 1100 Lighting device 1101 Case 1102 Light source 1103 Power storage device 1104 Ceiling 1105 Side wall 1106 Floor 1107 Window 1200 Indoor unit 1201 Case 1202 Air outlet 1203 Power storage device 1204 Outdoor unit 1300 Electric refrigerator-freezer 1301 Case 1302 Refrigerating room door 1303 Freezer compartment door 1304 Power storage device 1400 Tablet terminal 1401 Case 1402 Case 14 3 power storage device

Claims (3)

Amorphous PAHs,
S iO ₂ and
A current collector, and
Before SL SiO ₂ is negative electrode by which power storage device attached to the outer surface of the amorphous PAHs. Before SL SiO _2, the relative amorphous PAHs, a negative electrode for a power storage device according to claim 1 1 wt% to 3 at 0 wt% or less. The amorphous PAHs are spherical.
The negative electrode for a power storage device according to claim 1 or 2 .